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Goodman GMS96 Error Codes — Fault Code Guide

⚡ Quick Answer

Goodman GMS96 furnace error codes: all flash codes for the popular 96% AFUE single-stage furnace with causes and fixes.

⚡ AT A GLANCEScroll down for full repair guide
What it meansGoodman GMS96 furnace error codes: all flash codes for the popular 96% AFUE single-stage furnace with causes and fixes.
Most likely causeMost hvac faults come from power, airflow, sensor, drain, ignition, or control-board conditions. Start with the lowest-risk checks before replacing parts.
First checkConfirm the exact code, power-cycle once, inspect the obvious safety/flow path, then follow the step-by-step checks below.
⏱Repair time10-45 minutes for basic checks
🔧Part neededGoodman hot-surface igniter
Repair intent

Need this fixed instead of diagnosed?

Goodman GMS96 furnace error codes: all flash codes for the popular 96% AFUE single-stage furnace with causes and fixes.

Parts to price first

Check the part before you book service.

Goodman hot-surface igniter

Part: B1401015S / B1401015

Igniter part numbers named for ignition lockout faults.

Goodman condensate trap

Part: PCBBF118S / PCBBF133

Condensate trap references for pressure switch faults.

Goodman pressure switch

Part: B1370169 / B1370138

0.60 inch WC pressure switch references from the article.

Goodman flame sensor

Part: 20285401

Flame sensor listed in the parts table.

Furnace blower run capacitor

Capacitor size family named for slow blower and limit trips.

Goodman GMS96 Error Codes — What It Means

The Goodman GMS96 is a single-stage, 96% AFUE gas furnace and one of the most widely installed value-segment furnaces in North America. It uses a standard Goodman/Amana IFC control board with a diagnostic LED visible through the lower access panel. Like all 96% AFUE models, the GMS96 uses a secondary heat exchanger and condensate drain — making drain-related pressure switch faults the most common service issue.

Jump to Fix

Flash Code Quick Reference

FlashesMeaningMost Common Cause
1Lockout — retries exceededIgnition failure
2Pressure switch stuck openCondensate trap, hose, or inducer
3Pressure switch stuck closedHose routing or switch failure
4High limit device openDirty filter or blocked airflow
5Flame without call / roll-outGas valve or safety switch
6Reversed line polarityFix wiring at disconnect
7Gas valve energized — no callBoard or gas valve fault
8Low flame sensor signalClean flame sensor rod
9Igniter faultCheck igniter continuity

GMS96-Specific Issues

2 Flashes: Pressure Switch — GMS96

The GMS96 uses a plastic condensate trap assembly (Goodman part PCBBF118S and related variants). This trap is press-fit together and can develop hairline cracks at the joints over time, causing air leaks. Cracks may not be visible — submerse the trap in water while applying air pressure to check for bubbles.

The GMS96 pressure switch is typically rated at –0.60” WC. Check whether the inducer creates sufficient draft by temporarily connecting a manometer to the pressure switch port — draft should reach –0.60” or more during inducer operation.

4 Flashes: High Limit — GMS96

The GMS96 uses a low-static airflow design. It’s sensitive to filter restriction. Goodman recommends checking the filter monthly during heating season. The GMS96 also uses a PSC blower motor — the 7.5 µF or 10 µF run capacitor is the first thing to check when the blower seems slow. A capacitor that reads below rated value (>10% low) means the motor isn’t reaching full speed, which causes limit trips.

1 Flash: Ignition Lockout — GMS96

The GMS96 uses a silicon nitride hot-surface igniter (Goodman B1401015S or B1401015). Typical life is 5–7 years. If the unit is older, the igniter is the first thing to replace during a lockout diagnosis. Cold resistance should measure 40–90 ohms; a reading of OL means the element is cracked and open.

Step-by-Step Fix

For 2-flash / pressure switch:

  1. Power off the furnace at the disconnect.
  2. Locate the condensate drain trap (plastic U-shape, usually clear or white).
  3. Disconnect the outlet drain line and pour water through — it should drain freely.
  4. Inspect the trap body for cracks. If cracked, replace the trap assembly.
  5. Check the pressure switch hose from the inducer outlet — replace if cracked or brittle.
  6. Restore power and run a heat cycle.

For 1-flash / lockout:

  1. Remove the flame sensor rod (single screw in the burner box) and clean with steel wool.
  2. Verify gas supply is on and pressure is adequate.
  3. Test the igniter — measure resistance with a multimeter. Replace if OL.
  4. Power cycle and attempt to start.

Parts Often Needed

PartNotes
Hot-surface igniterGoodman B1401015S
Condensate trapGoodman PCBBF118S or PCBBF133
Pressure switch0.60” WC — Goodman B1370169 or B1370138
Flame sensorGoodman 20285401
Blower run capacitor7.5 or 10 µF / 370V

Technician Tips

Goodman furnaces use a simple LED flash system on the control board. The diagnostic LED is usually visible through the blower compartment window. Count the flashes between pauses — that’s your error code. One flash = normal operation. Two flashes = pressure switch fault. Three flashes = limit switch. Four flashes = flame sensor. Goodman flame sensors are notorious for carbon buildup — cleaning with emery cloth every 2-3 years prevents most lockout calls. The control board on GMS8 and GMSS9 models is particularly sensitive to voltage fluctuations — if you see multiple different codes, check the transformer output (should be 24VAC ±10%).

Prevention: Install a whole-house surge protector on the furnace circuit to prevent board damage from power spikes.

Need Replacement Parts?

Before ordering, match the HVAC part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.

When to Call a Pro

If you’re seeing 7-flash or 5-flash codes (gas valve faults), or if the furnace has rolled out, stop using the furnace and contact a licensed HVAC technician before restarting.


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